Sometimes questions that are getting closed due to been duplicates, have good answers (may be even answers better then the answers in the original question).
Would it be possible to copy good answers (have certain points and/or accepted) from the closed question to the live, original, question?
That way, all info is concentrated in one place.

2 Answers
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If you think that a question that has been closed as a duplicate has better answers than the original, flag it for moderator attention, and explain that you think it should be merged with the original (and why). If it is just one of the answers, explain that too, and they can make a judgment call. The more information they have, the better.

@Ben yes, that happens too. I've been tempted to do this when an old question has a perfectly good answer for the version(s) that were current at the time, but newer versions have more elegant or better performing options. The problem with version-specific answers is that one answer is the best answer for one version, but not necessarily for another.
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Aaron BertrandSep 4 '12 at 15:16

Questions can be merged from moderators, but the description for the merge tool says:

Questions should be merged when they are 99% identical and it would be beneficial to have all the answers from multiple duplicate questions in one place. This deletes answers, moves them to the target question, and leaves the current question as a stub with a link to its merge target.

Merging two questions is not necessarily done in all the cases a question is closed as duplicate of another one. It is done when the wording of the answers doesn't need to be changed to be adapted to the question to which the answer is moved.
For example, if a user asks the same question in two different Stack Exchange sites where the question is on-topic, and one of the questions is flagged, it could be migrated from the moderator handling the flag, and (in the site receiving the duplicate question) the moderators can merge the questions. In that way, the answers for the same question would be in the same place.